Production of precision bushings



Nov. 1, 1955 w. F. cousmo 2,722,047

PRODUCTION OF PRECISION BUSHINGS Filed May 5, 1951 ll-l United States Patent This invention relates'to the production of bushings. An object of this invention is to provide a methodfor the economical mass production of precision bushings. Another object of this invention is the production "from comparatively heavy steel stock, ,of bushings .of

predetermined dimensions within tolerances limited -.0Ol".

Another object of this invention is the production from strip stock, precision dimensioned bushings, with- .out any scrap resulting therefrom.

And another object of this inventionis themass production of automotive bushings which eliminates major cutting; reaming, grinding and other tool-operations-heretofore'employed in the production of similarelcments and thereby-reduce the cost thereof to a relatively small fraction of previous costs.

Other objects and advantages of this invention willbe apparent to those skilled in therartupon consideration of the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Referring to the drawings:

Fig. 1 is a perspective view of a strip of stock employed in the production of the bushings herein, illustrating at least one initial operation thereon, together with a blank severed therefrom;

Fig. 2 is an end elevation of a ring formed from the blank of Fig. 1;

Fig. 3 is a side elevation of the ring of Fig. 2, partly broken away;

Fig. 4 is a cross-section through a form of die arrangement for operating on the ring of Fig. 3, which embodies the method herein;

Fig. 5 is a view similar to Fig. 4, illustrating the completed die operation;

Fig. 6 is a side elevation of a completed bushing, partly broken away;

Fig. 7 is an end view of a stock strip subjected to a modified treatment;

Fig. 8 is a side elevation of another form of a finished bushing; and

Fig. 9 is a cross-section through a modified die arrangement which employs the novel method disclosed herein.

Certain automotive manufacturers demand vast quantitles of flanged bushings including predetermined dimensions within tolerance limits of $001. Heretofore such bushings were comparatively expensive due to the number of operations required for their production which included cutting, grinding and the like, and there was material residual scrap. The method herein disclosed eliminates most of the expensive tool operations and residual scrap.

Strip stock 10 has one of its sides coined to provide a feathered edge 12. Predetermined lengths are progressively sheared therefrom to provide blanks 14. Each of these segregated blanks 14 are, by the novel method here- 2 in, formed'into a completed precision dimensioned bushing, without any scrap therefrom.

The blank 14 is developed or formed into a cylinder or ring .16, by suitable die operations, to include a resultant longitudinal butt seam 18. The abutting faces of this seam are joined, in proper equipment, by a hydrogen copper braze 20.

The ring 16 at this stage is irregular in comparison to any required dimension or the contour of the bushing to be finished therefrom. Tolerance limits are not considered.

The steel cylinder 16 is then placed in a die member'22 with punch portion 24 extending into the feathered end of the ring. Asecond die member26, with punch 28 is then forced against the opposite end of the ring element. The second die member is also provided with flange determining recess 30 as a zone aboutthe punch 28. The diesare axially forced toward each other until the punch portions meet, which determines a space .or clearway 32 between the die members.

The metals in the ring are axially compressed and forced to an accurate diameter as determined by the seat .34 inthe die member 22, the zone recess 30 shapes an endless flange 36, and the bushing body excess metal is allowed to flow into the clearway 32. The volume of the flange 36.

*In this single press operation, a finished bushing 38 is formed, with precision inner and outer diameters, length and flange contour, together witha polished braze seam ,40.

, 'In' the event any slight bulge develop around the plane of punch contact, it is only necessary "to use a simple reamer to remove the same. Even this possibility can be avoided by the use of a punch 42 carried by the die 26, which extends entirely through the bushing, and providing a ring seat 44 in the die 22.

The flanges about the finished bushings 38 can be confined to any cross-sectional shape or the dies can be built to allow the metal to flow into the clearway 32 to fix the flange at any distance intermediate the ends of the bushing. This free flowing flange forming method is particularly useful when portions of the flange dimensions need not be severely accurate.

For some applications, it may be desirable to coin a second feathered edge 48 along the stock 10 opposite the edge 12.

It will now be apparent that the volume of metal within a finished bushing can be calculated and this exact volume supplied by a blank 14. The press forces and confines the bushing to finished form as determined by the dies with the metals flowing from the regions containing more than necessary for that region, into the flange formation, as well as removing the irregularities in the ring and in its brazed seam.

The seam is also finished with the metal flow or internal rearrangement of the fibers which are compressed from all directions throughout the bushing, resulting in a substantial overall increase in strength in the finished bushing. The resultant increase in strength is obtained by the use of compression forces throughout the method from the first coining operation to the finished bushing.

It is to be understood that the above detailed description of the present invention is intended to disclose an embodiment thereof to those skilled in the art, but that the invention is not to be construed as limited in its application by details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of being practiced and carried out in various ways without departing from the spirit of the invention. The language used in the specification relating to the operation and function of the elements of the invention is employed for purposes of description and not of limitation, and it is not intended to limit the scope of the following claims beyond the requirements of the prior art.

What is claimed and is desired to secure by United States Letters Patent:

1. The method of producing a flanged bushing comprising segregating a blank sheet of metal having a predetermined volume, developing said blank into a cylindrical ring with a longitudinal butt seam, joining the abutting faces of said seam by brazing, and axially compressing said ring while confining portions of the flow of the metal caused by said compression to form the body of said bushing while allowing the remainder including a portion of the brazing to freely cold flow into an integral flange about said bushing including a completely brazed butt seam therein, said flange being in a plane at right angles to said longitudinal butt seam, a portion of the metal in said flange being unrestrained by contact with a rigid surface during said cold flow.

2. The method set forth in claim 1 wherein portions of the metals both from the blank and from the braze are shaped into an endless flange.

3. The method set forth in claim 1 wherein the blank is of steel and the braze a non-ferrous metal, both of which are shaped into said finished bushing body and integral flange.

4. The method set forth in claim 1 wherein said bushcompressing said ring within said dies by pressure sufiicient to cause the cold metals in said blank and braze to be redistributed into a precision dimensioned bushing as determined by said dies, and allowing terminal portions of said metals to freely cold flow into a lateral clearway provided by the dies for that purpose to produce an integral flange of said metals about said bushing body.

6. The method set forth in claim 5 including the step of coining at least one edge of said blank prior to forming the cylindrical ring.

7. The method of producing a bushing to tolerances of at least one-one thousandth of an inch comprising the steps of segregating a blank sheet of metal having a predetermined volume, developing said blank into a cylindrical ring with a substantially longitudinal butt seam, and cold compressing said ring along the longitudinal axis while completely confining the metal ring between die members except for a lateral clearway portion between the die members allowing for free cold flow of the metal into an integral flange about said bushing.

8. The method of claim 7 in which the blank sheet is steel and the substantially longitudinal butt seam is joined by brazing.

References Cited in the file of this patent UNITED STATES PATENTS 652,845 Halifax July 3, 1900 653,900 Bray July 17, 1900 698,214 McKechnie Apr. 22, 1902 1,276,013 Beach Aug. 20, 1918 1,804,237 Steenstrup May 5, 1931 1,959,068 Stoll May 15, 1934 2,177,584 Salansky Oct. 24, 1939 2,269,839 Young Jan. 13, 1942 2,535,013 Freedom Dec. 19, 1950 

